U.S. patent application number 16/065496 was filed with the patent office on 2019-01-10 for icp mass spectrometer.
This patent application is currently assigned to SHIMADZU CORPORATION. The applicant listed for this patent is SHIMADZU CORPORATION. Invention is credited to Tomohito NAKANO.
Application Number | 20190013192 16/065496 |
Document ID | / |
Family ID | 59089925 |
Filed Date | 2019-01-10 |
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United States Patent
Application |
20190013192 |
Kind Code |
A1 |
NAKANO; Tomohito |
January 10, 2019 |
ICP MASS SPECTROMETER
Abstract
Provided is an ICP mass spectrometer which is able to
effectively discharge residual water by limiting the consumption of
Ar gas and a fluctuation in supply pressure of an Ar gas source at
the time of an Ar gas purge for a coolant system. The ICP mass
spectrometer is provided with: a device body part 1; a coolant
system 2 that supplies a coolant from a water source 20 to
to-be-cooled structure parts including a high-freqency power supply
12, a high-frequency coil 18, and a sample introduction part 13,
which need to be cooled; and an Ar gas supply system 3.
Intermediate valves V2, V3 are disposed on the downstream side of a
main valve V0, a purge gas channel 32 having a purge valve V1, and
a meeting point G of the purge gas channel 32. The to-be-cooled
structure parts are connected to a cooling-use pipe on the
downstream side of the intermediate valves V2, V3. A valve control
part 35 in configured to perform intermittent purge control of
repeating accumulation and discharge of the Ar gas on the upstream
side of the intermediate valves V2, V3 by intermediately opening
and closing the intermediate valves V2, V3 where the Ar gas is
being sent.
Inventors: |
NAKANO; Tomohito; (Kyoto,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHIMADZU CORPORATION |
Kyoto-shi, Kyoto |
|
JP |
|
|
Assignee: |
SHIMADZU CORPORATION
Kyoto-shi, Kyoto
JP
|
Family ID: |
59089925 |
Appl. No.: |
16/065496 |
Filed: |
June 24, 2016 |
PCT Filed: |
June 24, 2016 |
PCT NO: |
PCT/JP2016/068762 |
371 Date: |
June 22, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01J 49/0468 20130101;
H01J 49/0422 20130101; G01N 27/62 20130101; H01J 49/10 20130101;
H01J 49/105 20130101 |
International
Class: |
H01J 49/04 20060101
H01J049/04; H01J 49/10 20060101 H01J049/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 2015 |
JP |
2015-251434 |
Claims
1. An ICP mass analysis device characterized in that it comprises:
a device main body unit which supplies Ar gas for plasma generation
and sample gas, via a gas flow rate control unit which controls gas
flow rate, to a reaction tube of a plasma torch, ionizes the sample
gas by applying a high frequency voltage from a high frequency
power supply to a high frequency coil of said plasma torch, and
draws in generated sample ions through a sample introduction unit
to a mass analyzer to perform mass analysis; a cooling water system
in which water cooling piping is connected as a flow passage to
cooled structures which require cooling, including said high
frequency power supply, said high frequency coil and said sample
introduction unit, and which supplies cooling water from a water
source to said cooled structures; and an Ar gas supply system in
which gas piping is connected as a flow passage to said gas flow
rate control unit and which supplies Ar gas from an Ar gas source;
wherein, in said cooling water system, there is provided a master
valve which is connected as a flow passage on the upstream side of
said water cooling piping, a purge gas flow passage which branches
from said gas piping and is connected as a flow passage via a purge
valve at a location downstream of said master valve so as to merge
into said water cooling piping, and an intermediate valve which is
connected as a flow passage to said water cooling piping downstream
of the merging point of said purge gas flow passage; said cooled
structures are connected as a flow passage to said water cooling
piping downstream of said intermediate valve; a valve control unit
is provided, which performs interlocked opening/closing control of
said master valve, said purge valve and said intermediate valve;
and said valve control unit, when said master valve is placed into
a closed state and said purge valve is placed into an open state
and Ar gas is fed via the purge gas flow passage, performs
intermittent purge control whereby said intermediate valve is
intermittently opened and closed to repeat pressure accumulation
and release of Ar gas upstream of said intermediate valve.
2. An ICP mass analysis device as set forth in claim 1,
characterized in that, in the purge gas flow passage downstream of
said purge valve, there is provided a pipe resistance comprising a
pipe of the same diameter as or narrower diameter than the pipe
diameter of the purge gas flow passage.
3. An ICP mass analysis device as set forth in claim 1,
characterized in that the water cooling piping of said cooling
water system branches, downstream of the merging point of said
purge gas flow passage, into a bypass flow passage having a first
intermediate valve, and a high frequency power supply cooling flow
passage to which a second intermediate valve and said high
frequency power supply are connected as flow passages in series in
that order; said sample introduction unit and said high frequency
coil are connected as flow passages downstream of said bypass flow
passage and said high frequency power supply cooling flow passage;
and said valve control unit, when performing said intermittent
purge control, performs control whereby said first intermediate
valve and said second intermediate valve are simultaneously placed
into an open state, and said bypass flow passage and said high
frequency power supply cooling passage are simultaneously
purged.
4. An ICP mass analysis device as set forth in claim 1,
characterized in that the water cooling piping of said cooling
water system branches, downstream of the merging point of said
purge gas flow passage, into a bypass flow passage having first
intermediate valve, and a high frequency power supply cooling flow
passage to which a second intermediate valve and said high
frequency power supply are connected as flow passages in series in
that order; said sample introduction unit and said high frequency
coil are connected as flow passages downstream of said bypass flow
passage and said high frequency power supply cooling flow passage;
and said valve control unit, when performing said intermittent
purge control, performs control whereby said first intermediate
valve and said second intermediate valve are alternately placed
into an open state one at a time, and said bypass flow passage and
said high frequency power supply cooling flow passage are purged
one at a time.
Description
TECHNICAL FIELD
[0001] The present invention relates to an ICP mass analysis device
(also known as ICP-MS) which performs mass analysis by ionizing a
sample by means high frequency inductively coupled plasma.
BACKGROUND ART
[0002] ICP mass analysis devices are widely known as analyzers
capable of performing high sensitivity multi-element analysis, and
are used for elemental analysis in a broad range of fields (for
example, see Patent Literature 1). FIG. 6 illustrates the general
device configuration of an ICP mass analysis device.
[0003] ICP mass analysis device 100 mainly comprises a plasma torch
11, a high frequency power supply 12, a sample introduction unit
13, a mass analysis unit 14 comprising a mass analyzer, a gas flow
rate control unit 15, and a device main body control unit 16, which
make up a device main body unit 1. A cooling water system 2 and an
Ar gas supply system 3, which are necessary when using the ICP mass
analysis device 100, are furthermore connected to the device main
body unit 1.
[0004] The device main body unit 1 of the ICP mass analysis device
100 will be described in detail. The gas flow rate control unit 15
performs flow rate control of sample gas supplied from a nebulizer
19, Ar gas for plasma generation supplied via gas pipe 31 from the
Ar gas supply system 3, and the like. The plasma torch 11 comprises
a multiwall cylindrical reaction tube 17 to which plasma gas (Ar
gas) and sample gas are supplied under flow rate control by the gas
flow rate control unit 15, and a high frequency coil 18 wound onto
the outer circumference of the reaction tube 17.
[0005] The high frequency power supply 12 is connected to a high
frequency coil 18, and plasma is generated to ionize the sample gas
by applying high frequency voltage to the high frequency coil 18 in
a state where plasma gas and sample gas have been introduced into
the plasma torch 11.
[0006] The sample introduction unit 13 is kept in a reduced
pressure state by means of a vacuum pump (not illustrated) and is
designed to draw in ions of the sample, which has been ionized by
the plasma torch 11, along the central axis of a sampling cone 13a
through a sample introduction orifice. The mass analysis unit 14 is
maintained at a higher vacuum than the sample introduction unit 13,
and performs mass separation of the sample ions, which have been
draw in from the sample introduction unit 13, by means of a
quadrupole 14a or the like, and further performs mass analysis by
means of an ion detector 14b.
[0007] The device main body control unit 16 is composed of a
computer device comprising an input device (keyboard, mouse, etc.),
display device (liquid crystal panel, etc.) and input/output
interface, and performs configuration, command input and control of
the various units of device main body unit 1, and also performs
processing of data detected by the ion detector 14b.
[0008] In this sort of ICP mass analysis device 100, the reaction
tube 17 of the plasma torch 11 which generates plasma is brought to
a high temperature through induction heating, and in addition to
that, the sample introduction unit 13 located opposite the plasma
torch 11, the high frequency coil 18 and the high frequency power
supply board 12a contained within the high frequency power supply
12 also reach a high temperature.
[0009] Thus, excluding the reaction tube 17 of the plasma torch 11,
cooling is required for the sample introduction unit 13, high
frequency coil 18 and high frequency power supply 12, and cooling
water is supplied from a cooling water system 2 in order to prevent
corrosion and melting of the copper sampling cone 13a of the sample
introduction unit 13 and of the copper high frequency coil 18, and
to prevent breakdown due to heat generation of the high frequency
power supply board 12a contained within the high frequency power
supply 12.
[0010] MG. 7 is a drawing illustrating the piping system of cooling
water system 2 and Ar gas supply system 3. The water-cooling piping
of the cooling water system 2 is connected from a chiller (water
source) 20 having a circulation pump which feeds cooling water, via
a flow passage 21 to a master valve V0. The downstream side of the
master valve V0 is connected to a flow passage 22, and the flow
passage 22 branches in two and is connected to a first intermediate
valve V2 and a second intermediate valve V3. A flow passage (bypass
flow passage) 23 leading to the high frequency power supply 12 is
connected to the first intermediate valve V2. A flow passage (high
frequency power supply cooling flow passage) 24 for cooling the
high frequency power supply 12 (high frequency power supply board
12a) is connected to the second intermediate valve V3.
[0011] Flow passage (bypass flow passage) 23 and flow passage (high
frequency power supply cooling flow passage) 24 are used by
switching between them so as to prevent condensation from forming
on the high frequency power supply 12, and are controlled such that
the flow passage 24 side is opened when the high frequency power
supply is in an ON state and requires cooling, and the flow passage
23 side is opened when the high frequency power supply is in an OFF
state and does not require cooling. This flow passage switching
control is performed by the device main body control unit 16 in a
manner interlocked with the turning on and off of the high
frequency power supply 12, with control being performed such that
when one is opened, the other is closed, so that cooling water is
always flowing.
[0012] Flow passage 23 and flow passage 24 merge into flow passage
25, which then again branches into two and is connected to a flow
passage (sample introduction unit cooling flow passage) 26 which
cools the sample introduction unit 13 and a flow passage (high
frequency coil cooling flow passage) 27 which cools the high
frequency coil 18. After cooling the sample introduction unit 13
and high frequency coil 18, the flow passage 26 and flow passage 27
merge again into flow passage 28, and flow passage 28 is
recirculated to the chiller 20.
[0013] The portions of device main body unit 1 which require
cooling by the cooling water system 2 will be referred to as
"cooled structures." Among the three cooled structures consisting
of the high frequency power supply 12, sample introduction unit 13
and high frequency coil 18, in the sampling cone 13a of the sample
introduction unit 13, the orifice diameter of the central sample
introduction orifice gradually widens due to aging degradation,
which has an effect on analysis results, so the sampling cone 13a
is made replaceable as a consumable part.
[0014] FIG. 8 is a simplified cross-sectional view illustrating the
sample introduction unit 13. The sampling cone 13a is integrally
mounted on the outer surface side of cooling jacket 13b, and the
inner surface side of the cooling jacket 13b is removably secured
across a seal (not illustrated) so as to make the interface with
the sample introduction unit main body 13c liquid-tight. A cooling
flow passage 13d through which cooling water flows is formed in the
cooling jacket 13b, and cooling water is supplied via a connecting
flow passage 13e provided in the sample introduction unit main body
13c.
[0015] When the sampling cone 13a is to be replaced, the
replacement is made from the cooling jacket 13b, and thus when the
cooling jacket 13b is detached from the sample introduction unit
main body 13c, the cooling water flow passage is opened at the
interface between the connecting flow passage 13e and cooling flow
passage 13d.
[0016] If the cooling jacket 13b is to be detached in order to
replace the sampling cone 13a after cooling water has been fed into
the cooling water system 2, it is necessary to stop the supply of
water by closing the master valve V0, and to perform purging in
order to drain the residual water remaining in the various flow
passages past the master valve V0. For this purpose, a flow passage
for supplying purge gas is formed in the cooling water system
2.
[0017] Namely, as shown in FIG. 7, a purge gas flow passage 32 is
formed, which branches off from the middle of the Ar gas flow
passage 31 of the Ar gas supply system 3 and is connected at
merging point G to the flow passage 22 downstream of the master
valve V0 of the cooling water system 2. A purge valve V1 is
provided in the purge gas flow passage 32, and a check valve GV
which prevents cooling water backflow is interposed.
[0018] When the cooling jacket 13b of the sample introduction unit
13 is to be replaced, first, the master valve V0 is closed, after
which the purge valve V1, first intermediate valve V2 and second
intermediate valve V3 are all opened simultaneously, residual water
is drained by introducing Ar gas from purge gas flow passage 32
into flow passages 22 through 28, and then the cooling jacket 13b
is removed.
[0019] Similar Ar gas purging is also performed when performing
maintenance operations of the cooling water system 2 besides the
sample introduction unit 13. Furthermore, a similar draining
operation using Ar gas purging is performed not just during
maintenance operations but also in order to prevent corrosion due
to residual water when the device is stopped for a long period of
time.
PRIOR ART DOCUMENTS
Patent Literatures
[0020] Patent Literature 1: Japanese Unexamined Patent Application
Publication 2014-85268
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0021] However, the water cooling piping of the cooling water
system 2 has a large pipe diameter and relatively low pipe
resistance, so if purging with Ar gas is continued in order to
drain the residual water, the amount of Ar gas consumption will
become extremely high.
[0022] Furthermore, the same Ar gas that is used for purging the
cooling water system 2 is also used in the ICP mass analysis device
100 as the plasma gas (Ar gas), as the carrier gas for nebulizing
the sample, etc., and is supplied via the Ar gas supply system 3
from an Ar gas source consisting of a single gas bottle (or liquid
bottle).
[0023] At sites such as research facilities or factories where ICP
mass analysis devices are installed, the Ar gas source is in nearly
all cases used not just for a single ICP mass analysis device but
is rather shared among multiple devices (other analytical devices,
film growing devices, etc.).
[0024] For example, as shown in FIG. 9, the Ar gas source of the Ar
gas supply system 3 may be set up to supply Ar gas via an Ar gas
flow passage 31 not just to the ICP mass analysis device (ICP-MS)
100 but also to a second ICP-MS 101, another analytical device 102,
film forming device 103, etc.
[0025] In such an environment, when Ar gas purging is performed on
the cooling water system 2 of the ICP mass analysis device 100 as
described above, Ar gas will continuously flow into the water
cooling piping at a larger flow rate compared to when Ar gas is
supplied from the Ar gas flow passage 31 to the gas flow rate
control unit 15, and so the supply pressure of the Ar gas source
will gradually decrease. Specifically, it has been confirmed that
Ar gas supply pressure which is normally maintained by means of a
regulator at 480 KPa may drop to 400 KPa or less.
[0026] Therefore, there is an adverse effect upon the operation of
other devices to which Ar gas is supplied from the same Ar gas
source. In an environment where two ICP-MS devices 100 and 101 are
connected to a common Ar gas source as shown in FIG. 9, if Ar gas
is supplied to the cooling water system 2 for maintenance
operations on the first ICP-MS 100 while analysis is performed
simultaneously on the second ICP-MS 101, there is the concern that
proper gas flow rate control will become impossible due to the
reduction in Ar gas supply pressure, and problems such as the
plasma being extinguished may arise.
[0027] It is therefore an object of the present invention to
provide an ICP mass analysis device which makes it possible to
reduce the Ar gas consumption rate when performing Ar gas purging
of the cooling water system of the ICP mass analysis device, while
allowing residual water to be effectively drained.
[0028] It is a further object of the present invention to provide
an ICP mass analysis device capable to reducing fluctuation in the
supply pressure of the Ar gas source when Ar gas purging of the
cooling water system is performed.
Means for Solving the Problem
[0029] The ICP mass analysis device of the present invention, made
to resolve the aforementioned problem, comprises: a device main
body unit which supplies Ar gas for plasma generation and sample
gas, via a gas flow rate control unit which controls gas flow rate,
to a reaction tube of a plasma torch, ionizes the sample gas by
applying a high frequency voltage from a high frequency power
supply to a high frequency coil of said plasma torch, and draws in
generated sample ions through a sample introduction unit to a mass
analyzer to perform mass analysis; a cooling water system in which
water cooling piping is connected as a flow passage to cooled
structures which require cooling, including said high frequency
power supply, said high frequency coil and said sample introduction
unit, and which supplies cooling water from a water source to said
cooled structures; and an Ar gas supply system in which gas piping
is connected as a flow passage to said gas flow rate control unit
and which supplies Ar gas from an Ar gas source; wherein, in said
cooling water system, there is provided a master valve (V0) which
is connected as a flow passage on the upstream side of said water
cooling piping, a purge gas flow passage which branches from said
gas piping and is connected as a flow passage via a purge valve
(V1) at a location downstream of said master valve (V0) so as to
merge into said water cooling piping, and an intermediate valve
(V2, V3) which is connected as a flow passage to said water cooling
piping downstream of the merging point of said purge gas flow
passage; said cooled structures are connected as a flow passage to
said water cooling piping downstream of said intermediate valve
(V2, V3); a valve control unit is provided, which performs
interlocked opening/closing control of said master valve (V0), said
purge valve (V1) and said intermediate valve (V2, V3); and said
valve control unit, when said master valve (V0) is placed into a
closed state and said purge valve (V1) is placed into an open state
and Ar gas is fed via said purge gas flow passage, performs
intermittent purge control whereby said intermediate valve (V2, V3)
is intermittently opened and closed to repeat pressure accumulation
and release of Ar gas upstream of said intermediate valve (V2,
V3).
Effect of the Invention
[0030] According to the present invention, when draining of
residual water of the cooling water system is to be performed for
maintenance operations, etc., the valve control unit closes the
master valve and places the purge valve into an open state to feed
purge gas into the cooling water piping via the purge gas flow
passage, at which time the valve control unit performs control
whereby the intermediate valve is intermittently opened and
closed.
As a result, intermittent purging is performed, whereby pressure
accumulation and release of Ar gas are intermittently repeated
upstream of the intermediate valve.
[0031] Therefore, it becomes possible to perform purging by
intermittently flashing with Ar gas whereof the pressure has
accumulated in the piping upstream of the intermediate valve (which
is at about the same pressure level as the supply pressure upstream
of the purge valve), making it possible to effectively drain
residual water with a smaller quantity of Ar gas.
[0032] Furthermore, since there is no need to continuously (rather
than intermittently) release Ar gas as in the prior art, the total
consumption of Ar gas consumed during draining can also be
reduced.
[0033] In the invention as described above, it is preferable to
provide, in the purge gas flow passage downstream of the purge
valve, a pipe resistance comprising a pipe of the same diameter as
or narrower diameter than the pipe diameter of the purge gas flow
passage.
[0034] As a result, even when the purge valve is placed into an
open state, it is possible to suppress sudden inflow of Ar gas into
the purge gas flow passage, so the fluctuation in the supply
pressure upstream of the purge valve can be kept very low. It will
be noted that in the case of the same diameter, pipe resistance can
be increased by providing a longer flow passage length.
[0035] While the effect of reducing fluctuation in supply pressure
here becomes greater with a greater pipe resistance, since the rate
of inflow via the pipe resistance decreases, the pressure of
inflowing gas downstream of the pipe resistance will drop. If
purging is performed in a state of free discharge as in the prior
art rather than performing intermittent purging, depending on the
magnitude of the pipe resistance, the downstream gas pressure of
the purge gas will drop, and if the flow resistance of cooling
water is high, it will become impossible to drain residual
water.
[0036] In response to this, in the present invention, by ensuring
adequate time for accumulating pressure of Ar gas in accordance
with the magnitude of pipe resistance in the flow passage up to the
intermediate valve when the purge valve has been placed into an
open state, the pressure of Ar gas accumulated upstream of the
intermediate valve can be restored to about the same level as the
pressure in the piping upstream of the purge valve, so even if the
pipe resistance is increased, the operation of purging residual
water can be effectively performed with the accumulated
pressure.
[0037] Namely, not only can the fluctuation in supply pressure
upstream of the pipe resistance be reduced, but residual water can
be effectively drained with a smaller amount of Ar gas by
performing purging by flushing with Ar gas whereof the pressure has
accumulated upstream of the intermediate valve (to a pressure equal
to the pressure inside the piping upstream of the purge valve).
[0038] Furthermore, in the present invention as described above, a
configuration may be adopted wherein the water cooling piping of
the cooling water system branches, downstream of the merging point
of the purge gas flow passage, into a bypass flow passage having a
first intermediate valve, and a high frequency power supply cooling
flow passage to which a second intermediate valve and the high
frequency power supply are connected as flow passages in series in
that order; the sample introduction unit and the high frequency
coil are connected as flow passages downstream of the bypass flow
passage and the high frequency power supply cooling flow passage;
and the valve control unit, when performing intermittent purge
control, performs control whereby the first intermediate valve and
the second intermediate valve are simultaneously placed into an
open state, and the bypass flow passage and high frequency power
supply cooling passage are simultaneously purged.
[0039] Furthermore, instead of this, a configuration may be adopted
wherein the valve control unit, when performing intermittent purge
control, performs control whereby the first intermediate valve and
second intermediate valve are alternately placed into an open state
one at a time, and the bypass flow passage and high frequency power
supply cooling flow passage are purged one at a time.
[0040] In the ICP mass analysis device of the present invention, in
order to prevent condensation on the high frequency power supply,
the flow passage of the cooling water system is connected so as to
branch into a bypass flow passage and high frequency power supply
cooling passage, a first intermediate valve is arranged in the
bypass flow passage, and a second intermediate valve and the high
frequency power supply are arranged in the high frequency power
supply cooling flow passage. This first intermediate valve and
second intermediate valve are configured such that when the high
frequency power supply is off, the first intermediate valve is
opened and the second intermediate valve is closed, and when the
high frequency power supply is on, the first intermediate valve is
closed and the second intermediate valve is opened, so that only
one of the flow passages is in an open state and has cooling water
flowing through it, thereby preventing the occurrence of
condensation.
[0041] In the present invention, the first intermediate valve and
second intermediate valve that are used for switching the flow
passage in interlocking fashion with the turning on and off of the
high frequency power supply for the purpose of preventing
condensation, are also utilized for pressure accumulation for the
purpose of draining residual water.
[0042] Namely, independently of the primary opening/closing control
that is interlocked with the operation of the high frequency power
supply, when the valve control unit performs intermittent purge
control, control is performed whereby the first intermediate valve
and second intermediate valve are simultaneously placed into an
open state, and the bypass flow passage and high frequency power
supply cooling flow passage are simultaneously purged.
Alternatively, when performing intermittent purge control, the
valve control unit performs control whereby the first intermediate
valve and second intermediate valve are alternately placed into an
open state one at a time.
[0043] According to the present invention, effective draining
becomes possible simply by adding an intermittent purge control
flow (intermittent purging sequence) using the valve control
unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] FIG. 1 A drawing illustrating the device configuration of an
ICP mass analysis device according to the present invention.
[0045] FIG. 2 A drawing illustrating the piping system of the
cooling water system and Ar gas supply system in FIG. 1.
[0046] FIG. 3 A drawing illustrating an example of operating flow
of the present invention.
[0047] FIG. 4 A drawing illustrating an example of operating flow
of the present invention.
[0048] FIG. 5 A drawing illustrating an example of operating flow
for reference.
[0049] FIG. 6 A drawing illustrating the device configuration of a
conventional ICP mass analysis device
[0050] FIG. 7 A drawing illustrating the piping system of the
cooling water system and Ar gas supply system in FIG. 6.
[0051] FIG. 8 A simplified cross-sectional view illustrating the
sample introduction unit in an ICP mass analysis device.
[0052] FIG. 9 A drawing illustrating an example of the Ar gas
supply system in an ICP mass analysis device.
MODES FOR EMBODYING THE INVENTION
[0053] Embodiments of the present invention will be described below
using the drawings.
[0054] FIG. 1 is a drawing illustrating the device configuration of
an ICP mass analysis device A according to the present invention,
and FIG. 2 is a drawing illustrating the piping system of the
cooling water system and Ar gas supply system 3 in the ICP mass
analysis device A of FIG. 1. For constituent parts which are the
same as in the conventional ICP mass analysis device 100 described
in FIGS. 6 and 7, the same reference symbols will be assigned and a
portion of the description will be thus omitted.
[0055] In the ICP mass analysis device A according to the present
invention, the device main body control unit 16 composed of a
computer device as in the conventional ICP mass analysis device
100, is provided with a valve control unit 35 which performs
execution of a valve control program which implements Ar gas
purging based on opening and closing of a master valve V0, purge
valve V1, first intermediate valve V2 and second intermediate valve
V3.
[0056] This valve control unit 35, when draining of the cooling
water system 2 is to be performed, as a maintenance mode, performs
intermittent purge control in which the master valve V0, purge
valve V1, first intermediate valve V2 and second intermediate valve
V3 are operated according to an operation flow as described below.
Namely, when master valve V0 is placed into a closed state and
purge valve V1 is placed into an open state and Ar gas is fed into
the cooling water system 2 via the purge gas flow passage 32, the
first intermediate valve V2 and second intermediate valve V3 are
maintained in a closed state until the time necessary for pressure
accumulation (pressure accumulation time T) has elapsed and are
then placed into an open state, after which they are again placed
into a closed state, which is maintained until pressure
accumulation time T has elapsed, after which the valves are placed
into an open state. The operation of opening and closing
intermittently in this manner is repeated to perform control for
repeating the pressure accumulation and release of Ar gas.
[0057] Furthermore, in the present embodiment, a pipe resistance 36
which restricts inflow of gas is provided in the purge gas flow
passage 32 downstream of the purge valve V1. The pipe resistance 36
is selected to have a magnitude of resistance sufficient to prevent
sudden pressure fluctuation upstream of the purge valve V1 when the
purge valve V1 is opened.
[0058] Specifically, in the middle of the purge gas flow passage 32
formed from gas pipe with an inside diameter of 4 mm, a pipe with a
narrower inside diameter of 0.5 mm is connected as a (coiled) pipe
resistance 36 with a length of 1 m, thereby increasing the pipe
resistance of the purge gas flow passage 32.
[0059] Connecting the pipe resistance 36 causes the gas flow rate
downstream of the pipe resistance 36 to decrease, so the time
required for pressure accumulation in the intermittent purge
control described above (pressure accumulation time T), i.e. the
waiting time until the accumulated Ar gas pressure becomes about
the same as the pressure upstream of the purge valve V1, is preset
in accordance with the magnitude of the pipe resistance 36 on the
basis of preliminary experiments. Furthermore, the time during
which the intermediate valves V2, V3 are opened (opening time F) is
also set in advance. The description here will assume that the
pressure accumulation time T has been set at 10 seconds and the
opening time F has been set at 5 seconds.
[0060] Furthermore, the purge count n (used as the argument n in
the operation flow described later) is also set in advance. In the
following embodiment example, it will be assumed that this was set
so as to perform five purges (n=5).
[0061] Next, the gas purge operation flow under the aforesaid
conditions will be described.
(Operation Flow-1)
[0062] FIG. 3 is a flow chart explaining an example of the gas
purging operation flow using the valve control unit 35 of the ICP
mass analysis device A.
[0063] When an input operation is performed to start maintenance
mode with the input device of the device main body control unit 16
in order to perform draining of the cooling water system 2, the
parameter n which counts the number of purges is set to the initial
value 0, the master valve V0 closes, and the first intermediate
valve V2 and second intermediate valve V3 are closed nearly
simultaneously. It will be noted that the purge valve V1 is closed
to begin with (ST101).
[0064] Next, the purge valve V1 is opened and the open state is
maintained until a preset pressure accumulation time T (10 seconds)
elapses. As a result, the Ar gas of the purge gas flow passage 32
is accumulated until its pressure reaches the same level as the
pressure upstream of the purge valve V1 (ST102). The first time,
since cooling water remains downstream of the check valve GV, by
way of exception, Ar gas is accumulated in the pipe only up to the
check valve GV, but in the second and subsequent pressure
accumulation described below, pressure accumulation occurs also
downstream of the check valve GV.
[0065] Next, the first intermediate valve V2 and second
intermediate valve V3 are opened for a preset opening time F (5
seconds) to perform purging. During this time, the purge valve V1
is maintained in an open state, and Ar gas which has accumulated in
the purge gas flow passage 32 is released and flows downstream,
draining the residual water in the downstream direction.
[0066] At this time, 1 is added to the purge count parameter n
(ST103).
[0067] Next, the current purge count is checked on the basis of the
parameter n (ST104). If the purge count parameter n is less than 5,
the processing of ST102 through ST104 is repeated.
[0068] Once parameter n becomes 5, control proceeds to ST105.
[0069] After confirming that the set number (n=5) of purges has
been carried out in ST104, the master valve V0 and purge valve V1
are closed (ST105). Purging is thereby ended.
[0070] The first intermediate valve V2 and second intermediate
valve V3 are then also closed (ST106). Device operation is thereby
completed.
[0071] According to the above procedure, draining can be
efficiently carried out through gas purging while reducing the
consumption of Ar gas.
(Operation Flow-2)
[0072] FIG. 4 is a flow chart explaining another example of the gas
purge operation flow using the valve control unit 35 of the ICP
mass analysis device A. The difference from "operation flow-1"
described above is that the first intermediate valve V2 and second
intermediate valve V3 are alternately opened and closed in order to
carefully purge flow passage (bypass flow passage) 23 and flow
passage (high frequency power supply cooling flow passage) 24 one
by one. The operation in this case is as follows.
[0073] When an input operation to start maintenance mode is
performed using the input device of the device main body control
unit 16, the parameter n which counts the number of purges is set
to the initial value 0, the master valve V0 closes, and the first
intermediate valve V2 and second intermediate valve V3 are closed
nearly simultaneously. It will be noted that the purge valve V1 is
closed to begin with (ST201).
[0074] Next, the purge valve V1 is opened and the open state is
maintained until a preset pressure accumulation time T (10 seconds)
elapses. As a result, the Ar gas of the purge gas flow passage 32
is accumulated until its pressure reaches the same level as the
pressure upstream of the purge valve V1 (ST202). The first time,
since cooling water remains downstream of the check valve GV, by
way of exception, Ar gas is accumulated in the pipe only up to the
check valve GV, but in the second and subsequent pressure
accumulation described below, pressure accumulation occurs also
downstream of the check valve GV.
[0075] Next, the first intermediate valve V2 is opened for a preset
opening time F (5 seconds) to perform purging. During this time,
the purge valve V1 is maintained in an open state, while the master
valve V0 and second intermediate valve V3 are maintained in a
closed state. As a result, the Ar gas which has accumulated in the
purge gas flow passage 32 is released and flows downstream,
draining the residual water in the downstream direction. At this
time, 1 is added to the purge count parameter n (ST203).
[0076] Next, with the purge valve V1 remaining open, the first
intermediate valve V2 is closed, and the open state is maintained
until a preset pressure accumulation time T (10 seconds) elapses.
As a result, the Ar gas of the purge gas flow passage 32 is
accumulated until its pressure reaches the same level as the
pressure upstream of the purge valve V1 (ST204).
[0077] Next, the second intermediate valve V3 is opened for a
preset opening time F (5 seconds) and purging is performed. During
this time, the purge valve V1 is maintained in an open state, while
the master valve V0 and first intermediate valve V2 are maintained
in a closed state. As a result, the Ar gas which has accumulated in
the purge gas flow passage 32 is released and flows downstream,
draining the residual water in the downstream direction. The purge
count parameter n remains unchanged at this time (ST205).
[0078] Next, the current purge count is checked on the basis of the
parameter n (ST206). If the purge count parameter n is less than 5,
the processing of ST202 through ST205 is repeated.
[0079] Once parameter n becomes 5, control proceeds to ST207.
[0080] After confirming that the set number (n=5) of purges has
been carried out in ST206, the master valve V0 and purge valve V1
are closed (ST207). Purging is thereby ended.
[0081] The first intermediate valve V2 and second intermediate
valve V3 are then also closed (ST208). Device operation is thereby
completed.
[0082] According to the above procedure, draining can be
efficiently carried out through gas purging while reducing the
consumption of Ar gas.
(Reference Operation Flow)
[0083] Two operation flows constituting embodiments of the present
invention were described above. The above-described operation
flows-1 and 2 make it possible to achieve a reduction in Ar gas
consumption and a reduction in supply pressure fluctuation of the
Ar gas supply system, which are the two object of the present
invention.
[0084] By contrast, when the object is only the latter--reduction
in supply gas fluctuation, if the flow resistance of cooling water
flowing through the water cooling piping is low and draining is
possible with the pressure of the purge gas which has passed
through the pipe resistance 36, the device configuration can be
simplified.
[0085] Namely, it is possible to reduce supply pressure fluctuation
simply by using the pipe resistance 36 of the purge gas flow
passage 32, without performing intermittent purge control. The
reference operation flow for this case is shown in FIG. 5.
[0086] When an input operation is performed to start maintenance
mode with the input device of the device main body control unit 16,
the master valve V0 closes, and the first intermediate valve V2 and
the second intermediate valve V3 are closed nearly simultaneously.
It will be noted that the purge valve V1 is closed to begin with
(ST301).
[0087] Next, the purge valve V1, first intermediate valve V2 and
second intermediate valve V3 are opened simultaneously, and the
open state is maintained until a preset opening time F (for
example, 30 seconds) elapses (ST302). The master valve V0 is
maintained in a closed state. At this time, Ar gas flows in
continuously, but the inflow of gas is restricted due to the
existence of the pipe resistance 36, so the supply pressure does
not drop significantly, making it possible to prevent adverse
effects due to pressure fluctuation upstream of the purge valve
V1.
[0088] Next, after the opening time has elapsed, the master valve
V0, purge valve V1, first intermediate valve V2 and second
intermediate valve V3 all close, whereby operation of the device is
completed (ST303).
[0089] Embodiments of the present invention have been described
above, but the present invention is not limited to these
embodiments and of course includes various other configurations
that do not depart from the gist of the present invention.
[0090] For example, in the embodiments described above, a structure
involving switching the first intermediate valve V2 of flow passage
(bypass flow passage) 23 and the second intermediate valve V3 of
flow passage (high frequency power supply cooling flow passage) 24
was employed, but the invention can also be applied with a cooling
water system of a simpler structure in which no bypass flow passage
is provided and only a single intermediate valve is arranged in a
single flow passage.
[0091] Furthermore, in the embodiments described above, a pipe
resistance 36 was provided in the purge gas flow passage 32 to
reduce pressure fluctuation on the upstream side, but if instead no
pipe resistance 36 is provided and only intermittent purge control
is performed using the valve control unit 35, intermittent pressure
fluctuation of upstream supply pressure will occur, but this is
still effective because the magnitude of supply pressure
fluctuation can be reduced as compared to the free-flowing state of
the prior art.
FIELD OF INDUSTRIAL APPLICATION
[0092] The present invention can be employed for ICP mass analysis
devices.
DESCRIPTION OF REFERENCE SYMBOLS
[0093] A ICP mass analysis device [0094] 1 Device main body unit
[0095] 2 Cooling water system [0096] 3 Ar gas supply system [0097]
11 Plasma torch [0098] 12 High frequency power supply [0099] 13
Sample introduction unit [0100] 14 Mass analysis unit (mass
analyzer) [0101] 15 Gas flow rate control unit [0102] 16 Device
main body control unit [0103] 18 High frequency coil [0104] 19
Nebulizer [0105] 20 Chiller (water source) [0106] 23 Bypass flow
passage [0107] 24 High frequency power supply cooling flow passage
[0108] 26 Sample introduction unit cooling flow passage [0109] 27
High frequency coil cooling flow passage [0110] 32 Purge gas flow
passage
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